Unwinder for as-spun elastomeric fiber

ABSTRACT

The invention provides an over-end take off device (OETO) for unwinding elastomeric fiber. The invention further provides a method for unwinding elastomeric fiber for downstream processing.

[0001] This application is a continuation of U.S. patent applicationSer. No. 10/100,811, filed March, 19, 2002, currently pending.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a fiber unwinding device, andmore specifically to a device that minimizes average tension levels andtension variations of a plurality of elastomeric fibers beingtransported to a downstream fiber processing operation.

[0004] 2. Description of Background Art

[0005] The most common method of unwinding fiber from a cylindricalmandrel (or “package”) in manufacturing processes is referred to as“rolling takeoff”. When the package is exhausted the empty mandrel mustbe removed and a new package installed. This operation requires shuttingdown the manufacturing line causing unproductive downtime.

[0006] Another method often utilized, the over end takeoff (OETO)method, allows continuous operation, because the terminating end of thefiber wound on an active package can be attached to the leading end ofthe fiber wound on a standby package. This allows the active package tobe fully exhausted at which point the standby package becomes the activepackage, all without any process interruption. However, unacceptablevariations in threadline tension are common with OETO.

[0007] Research Disclosure, p. 729, November 1995, item #37922,discloses an OETO system in which elastomeric fiber is passed through asystem comprising a relaxation section and motor driven nip rolls,before being fed to the manufacturing line. The relaxation section,extending between the package and the nip rolls, is stated to suppresstension variations. However, fibers that exhibit high cohesive forces(generally referred to as “tack”) display unusually high variations infrictional forces and tension levels as the package unwinds. Theslackness of the thread line in the relaxation region can vary and canresult in temporarily excessive amounts of filament being unwound fromthe package. This excess fiber can be drawn into the nip rolls and woundup on itself leading to entanglement or breakage of the threadlinerequiring the manufacturing line to be stopped. The high level of tackcontributes to the possibility of the excess fiber adhering to itselfand to the nip rolls. The OETO device can also be configured such thatthe fiber horizontally traverses the relaxation section. In this case,the fiber then travels through nip rolls whose axes are vertical.However, in this configuration, the fiber in the region between thepackage and the nip rolls can sag. This sagging allows the threadlineposition on the nip rolls to become unstable and can result ininterference between adjacent threadlines.

[0008] U.S. Pat. Nos. 3,797,767; 3,999,715 and 6,158,689 disclose theuse of spirally grooved rolls in fiber winding machines in order toimpart a specified pitch angle to a fiber as it is wound on a package.The use of grooved rolls for maintaining positional stability among aplurality of thread lines on a single roll is not described.

[0009] The aforementioned problems make the processing of high tack,elastomeric fibers particularly problematic. Fiber tack and itsassociated problems have been addressed by using topical fiber additives(prior to winding) or by unwinding the package and re-winding it on anew mandrel. However, both approaches add additional expense.Furthermore some applications (such as diaper manufacturing) require theuse of as-spun fiber that is substantially finish-free and,consequently, exhibits high tack.

[0010] A fast and reliable method of removing high tack elastomericfiber from a package is still needed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 schematically illustrates the fiber unwinding testequipment used to obtain the data in Examples 1-4.

[0012]FIG. 2 shows a perspective drawing of a preferred embodiment of anOETO unwinding device.

[0013]FIG. 3 illustrates a perspective view of a portion of an unwindingdevice of the invention including some of the packages, threadlineguides and the first driven roll.

[0014]FIG. 4 is a top view of an unwinding device of the invention.

[0015]FIGS. 5A and 5B, are back and side views, respectively, of anunwinding device of the invention.

SUMMARY OF THE INVENTION

[0016] The present invention provides, in a first embodiment, anunwinder comprising

[0017] a) a frame;

[0018] b) a fiber package holder affixed to said frame for holding apackage of fiber about a rotational axis such that at least one fibercan unwind from said fiber package in a direction defining an acuteangle with the rotational axis of the fiber package;

[0019] c) a driven take-off roll for unwinding fiber from the fiberpackage at a predetermined take-off rate:

[0020] d) a first fiber guide for directing fiber unwound from the fiberpackage towards the driven take-off roll, said first fiber guidepositioned on said frame such that;

[0021] i. a distance (d) from the first fiber guide to the end of thefiber package facing such first fiber guide, measured on the linedefined by the rotational axis of the fiber package, is equal to:

[0022] 1) at least about 0.41 meter for fiber with tack of greater thanabout 2 grams OETO and less than about 7.5 grams OETO; or

[0023] 2) from about 0.71 meter to about 0.91 meter for fiber with tackgreater than about 7.5; and

[0024] ii. an angle (θ), defined by the intersection of imaginary linescorresponding, respectively, to the rotational axis of the package andthe central axis of the fiber guide inlet orifice is equal to:

[0025] 1) 0° to about 30° for fibers with tack greater than about 2grams OETO and less than about 7.5 grams OETO; or

[0026] 2) 0° to about 100 for fibers with tack levels greater than about7.5 grams OETO.

[0027] The unwinder of the invention may further include additionalfiber guides between package and said take-off roll.

[0028] The unwinder of the invention preferrably further includes asecond fiber guide positioned between the fiber package and the firstfiber guide for directing fiber unwound from the fiber package. Morepreferrably, the unwinder of the invention further comprises a thirdfiber guide positioned between the first fiber guide and the driventake-off roll.

[0029] The unwinder of the invention may also include a fourth fiberguide positioned between the third fiber guide and the driven take-uproll.

[0030] At least one of the fiber guides may be a grooved roll or thedriven take-off roll may be a grooved roll.

[0031] In a preferred embodiment, at least one fiber guide is a staticcircular guide having a wear-resistant surface for contacting the fiber.The circular fiber guide preferably has a wear-resistant inner surfacesuch that the wear-resistant surface is the inner surface of an annulus.

[0032] In a second embodiment, the invention provides a method forunwinding fiber comprising the steps of:

[0033] a. holding a fiber package about a rotational axis such that atleast one fiber can unwind from the fiber package in a directiondefining an acute angle with the rotational axis of the fiber package;

[0034] b. unwinding fiber from the fiber package of step (a) at acontrolled predetermined rate;

[0035] c. controlling the direction of said fiber of step (a) by passingthe fiber through a first fiber guide; and

[0036] d. controlling the distance (d) from said first fiber guide tothe end of said fiber package facing said fiber fiber guide, measured onthe line defined by the rotational axis of the fiber package, such thatsaid distance (d) is equal to:

[0037] i. at least about 0.41 meter for fiber with tack of greater thanabout 2 grams OETO and less than about 7.5 grams OETO; or

[0038] ii. from about 0.71 meter to about 0.91 meter for fiber with tackgreater than about 7.5;

[0039] e. controlling an angle (θ), defined by the intersection ofimaginary lines corresponding, respectively, to the rotational axis ofthe package and the central axis of said first fiber guide that isperpendicular to the plane of the orifice, such that said angle (θ) isequal to:

[0040] i. 0° to about 30° for fibers with tack greater than about 2grams OETO and less than about 7.5 grams OETO; or

[0041] ii. 0° to about 10° for fibers with tack levels greater thanabout 7.5 grams OETO.

DETAILED DESCRIPTION OF THE INVENTION

[0042] With reference to FIG. 1, a fiber package 10 is maintained in adesired orientation by a cylindrical rod (not shown). The diameter ofthe rod is smaller than the diameter of the open core of the packagesuch that the package can be slid over the suitably positioned rod andsuch that the fiber can be unwound from the package by over end takeoff.The fiber is then directed, in sequence, through a static guide 20having a substantially circular orifice; a driven roll 30 around whichthe fiber is wrapped 360°, or less; and a second, driven take-up roll orset of rolls 50. The static guide is typically an orifice whose innersurface can be a highly polished ceramic material. Such a surface canprovide excellent wear resistance and low friction. The take-up roll orrolls 50 representing that part of the manufacturing process equipmentto which the fiber is being supplied, is/are rotated at a speedrelatively higher than the first motor-driven roll, so as to provide thedesired draft. A distance (d) between the package and the static guide,which is at least about 0.43 meter and preferably not more than about0.91 meter, can be maintained for operation with high tack fibers. Anacute angle (θ), defined by the intersection of the imaginary linescorresponding, respectively, to the rotational axis of the package andthe central axis of the static guide orifice that is perpendicular tothe plane of the orifice, is preferably maintained between 0 and about300 for operation with high tack fibers. Means for stabilizing theposition of the threadline on the first driven roll can be provided by,for example, use of one or more additional guides 60, 70, 80 and/or aplurality of grooves in the surface of the first driven roll 30 whereinsaid grooves are substantially perpendicular to the roll axis andsubstantially parallel to the direction of travel of the threadline.

[0043] Distances less than 0.41 meter can result in undesirably largetension variations. These variations can cause process controldifficulties and can also lead to thread line breakages. Distanceslonger than 0.91 meter make the unwinding equipment less compact andergonometrically less favorable. As the level of tack exhibited by thefiber increases, the minimum allowable distance, d, increases. Forfibers with tack levels greater than about 2 and less than about 7.5, dis preferably at least about 0.41 meter; and for fibers with tack levelsgreater than about 7.5, d is preferably at least about 0.71 meter.

[0044] As the level of tack exhibited by the fiber increases, themaximum allowable angle, θ, decreases. The directional change of thethreadline, as it passes through the first static guide, as measured interms of 0, is preferably limited to between 0° and about 30° for fiberswith tack levels greater than about 2 and less than about 7.5, andbetween 0° and about 100 for fibers with tack levels greater than about7.5. Larger angles can result in excessive variations in thread linetension and draft, or even threadline breakage.

[0045] The desired thread line positional stability can be assured byproviding grooves in the surface of the first driven roll. Such groovesalso allow closer spacing of the threadlines, thereby minimizing thedimensions of the equipment. The resulting stability of the threadlineposition also allows operator intervention to correct a threadlineproblem, while the process is running, with less risk of disturbingadjacent thread lines.

[0046] Threadline guides can be used in addition to, or instead of,grooved rolls to impart thread line stability and to direct thethreadline along a desired path. Of the various threadline guidesavailable, captive, rolling guides are preferred. The use of a single,first motor-driven roll described above is found to give outstandingprocess performance without the need for employing the more mechanicallycomplex and expensive nip rolls described in Research Disclosure, item37922, cited above. A wrap of 360° or less of the thread line around theroll minimizes fiber-on-fiber contact and the possibility of fiberdamage associated with such contact. Less than 360° contact between thethread line and roll can be achieved by the appropriate positioning of athreadline guide placed immediately after the roll to lift the fiber offthe roll surface short of a complete 360° wrap.

[0047] The process by which the unwinder of this invention can beoperated involves the following steps, with reference to FIGS. 2, 3, 4,5A and 5B: a) placing the fiber packages on their respective mountingrods; b) tying the leading end of fiber from each standby package 300′or 400′ to the trailing fiber end of its corresponding active package300 or 400, respectively; c) directing the leading fiber end of eachactive package through its respective static guide 100 or 100′, thenthrough a wrap of 360° or less around the first driven roll 800 and thencausing it to be engaged by a take-up device not shown in FIGS. 2-5(identified as 50 in FIG. 1) (this device, typically a driven roll orset of driven rolls, represents that element of the manufacturingprocess which first engages the fiber as it exits the unwinder); d)initiating rotation of the first driven roll 800 and take-up device (notshown); while e) controlling the surface speeds of each such that thesurface speed of roll/s (not shown) exceeds that of roll 800 by thepercentage corresponding to the desired fiber elongation (or draft); f)replacing each active package 300 or 400, as it becomes exhausted, withwhat now becomes a standby package; and g) tying the leading fiber endof this new standby package 300 or 400 with the trailing end of the now,active package 300′ or 400′. Repeating steps f and g (or b), asrequired, allows uninterrupted operation. As previously described,positional stabilization of the threadlines can be achieved by the useof a grooved roll 800, and/or additional threadline guides. In the eventthat a grooved roll is employed, step c, above, also includes placingeach fiber in its corresponding groove. In the event that additionalthreadline guides are employed, additional steps must be added to theabove procedure to thread each fiber through its respective, additionalguides in the sequence that such guides are encountered.

[0048] FIGS. 2-5A&B illustrate a preferred embodiment of an OETOunwinding device for high tack spandex fiber. For the purpose ofimproved clarity, the threadlines are not shown. As presented in FIGS.2, 3 and 4, the OETO fiber unwinding system has the capacity to feed amanufacturing line with eight (8) threadlines, requiring a capacity toaccommodate sixteen (16) packages. Each threadline supplied from anactive package to the first, static guide 100 or 100′ is kept in thehorizontal plane. The packages are mounted in vertical tiers 200, eachtier holding four (4) packages 300, 300′, 400 and 400′. The fourpackages are arranged in pairs, each pair consisting of one active 300or 400 and one standby 300′ or 400′ package.

[0049] With reference to FIGS. 4, 5A and 5B, each threadline leads froman active package 300 or 400 through a first static guide 100 or 100′and then through a captive rolling guide 500, at the horizontal centerof the unwinding device. All three of these elements are locatedsubstantially on the same horizontal plane.

[0050] Referring to FIG. 5A, the threadline is then turned up or down,depending upon the tier from which it originated, to the vertical centerof the unwinding device. At the vertical center of the unwinding device,each threadlines is fed through its respective captive rolling guide 600and then directed horizontally through its respective static guide 700.Finally, the threadlines are wrapped 360°, or less, around a horizontaldriven roll 800. The driven roll 800 (shown in FIG. 3) is illustratedwith eight grooves 900, through which the threadlines run. The groovedepths are 0.38 mm and the spacing between the grooves is 15 mm. Groovesare an optional feature of horizontal driven roll 800; the driven rollmay alternatively have a smooth surface.

[0051] The following examples include experiments with Lycra® XA® fibershaving no topically applied finish.

EXAMPLE 1

[0052] The test equipment used in obtaining the data for this and thefollowing examples, could be configured in various ways, such asoptionally including or excluding certain design elements and changingthe sequence of certain elements. The equipment configuration employedfor this example, with reference to FIG. 1, was comprised of thefollowing elements, listed in the order in which they were encounteredby the moving threadline: fiber package 10, static guide 20, first,driven roll 30, tension sensor 40, and driven take-up rolls 50.

[0053] The test equipment geometry and other experimental testconditions are summarized below:

[0054] The distances between the static guide and the first driven roll,between the first driven roll and the tension sensor and between thefirst driven roll and the take-up roll were 0.22, 1.94 and 2.1-3.4meters, respectively. In this example, the first driven roll, having adiameter of 8.89 cm., was not grooved. The threadline was maintained inthe horizontal plane (relative to ground), and its directional changewithin that horizontal plane as it passed through the static guide, wasmaintained constant at 0° θ. The distance between the package and firstguide was varied. The threadline was wrapped 360° around the firstdriven roll. The threadline draft was controlled at 2.15×by maintainingthe surface speeds of the first roll at 93.4 meter/min, and the surfacespeed of the takeup rolls at 294.3 meters/min.

[0055] Tension data (expressed in grams) were collected with a ModelPDM-8 data logger, and a Model TE-200-C-CE-DC sensor (ElectromaticEquipment Co.). All tension measurements were averaged over five-minuterun time using a data sampling frequency of approximately 82samples/sec.

[0056] “Mean range tension” was determined as follows: within every1.25-second interval of the tension measurement, the minimum and maximumtension levels were recorded (yielding 103 data points). Mean rangetension was calculated by averaging the differences (between the minimumand maximum values) over the 5-min run.

[0057] The fiber evaluated in this test was as-spun Lycra® XA spandex (aregistered trademark of E.I. du Pont de Nemours and Company) having alinear density of 620 dtex (decigram per kilometer).

[0058] Table 1 shows the thread line tension variations, as measured atthe sensor, as the distance, d, between the package and the static guidewas varied over a distance between about 0.25 and 0.81 meter. TABLE 1Distance Mean Range Tension Max. Tension (meter) (grams) (grams) 0.2716.90 50.00 0.28 17.60 50.00 0.30 17.80 50.00 0.33 16.30 50.00 0.3616.30 49.00 0.38 14.50 50.00 0.41 13.70 48.40 0.43 13.30 38.00 0.4612.40 37.10 0.48 12.20 44.70 0.51 11.60 36.30 0.53 11.60 36.70 0.5611.60 30.40 0.58 11.80 32.60 0.61 10.00 28.80 0.64 10.60 34.30 0.6610.60 25.30 0.69 10.40 34.30 0.71 10.60 29.80 0.74 10.00 28.40 0.7610.40 29.40 0.79 10.80 27.80 0.80 10.80 34.50

[0059] Table 1 demonstrates that thread line tension (expressed eitheras the mean range or the maximum tension) decreases as the distancebetween the package and the static guide is increased. Minimum tensions,not shown in the table ranged from about 0.6 to 1.4 grams. Unexpectedly,it has been discovered that there is a minimum distance of about 0.41meter below which the absolute level of tension and the tensionvariability (as observed by plotting, for example, maximum tensionversus distance) rises to an unacceptably high level identifiable by theoccurrence of threadline breakages which are usually preceded by arelatively abrupt increase in mean range tension.

EXAMPLE 2

[0060] The same test equipment as described in Example 1, but configuredto more closely correspond to the preferred embodiment of the OETOunwinder design was utilized. With reference to FIG. 1, the equipmenthad the following elements in the order in which they were encounteredby the moving threadline: fiber package 10, captive rolling guide 60,static guide 20, captive rolling guide 70, first, driven roll 30,captive rolling guide 80, tension sensor 40, and driven take-up rolls50.

[0061] The distances between the static guide and the first driven roll,between the first driven roll and the tension sensor, and between thefirst driven roll and the takeup rolls were 0.43, 0.51 and 2.43 meters,respectively. The first driven roll was a single roll having a singlegroove with a depth of 0.38 mm. The threadline was again maintained inthe horizontal plane. The distance between the package and the staticguide was held constant at 0.65 meter while the angle, θ, was varied.Threadline draft was maintained at 4×by controlling the first drivenroll and the takeup rolls, respectively, at surface speeds of 68.6 and274.3 meters/min.

[0062] In addition to monitoring threadline tension as in Example 1,tension spikes were also recorded. “Tension spikes” are the averagenumber of sudden increases in tension greater than 25 grams abovebaseline tension in a 5-min period.

[0063] Various as-spun Lycra® XA® spandex fibers, exhibiting differentlevels of tack, were evaluated. Tack levels were characterized bymeasuring the OETO tension (in grams) by the following method: The fiberpackage and a ceramic pig tail guide were mounted 0.61 meter apart, suchthat the axes of each were directly in line. The fiber is pulled off thepackage over end at a threadline speed of 50 meters/min, through theguide, and through a tension sensor.

[0064] Table 2 shows the threadline tension variations as the angle θincreased; where θ is defined as the acute angle made by theintersection of the imaginary lines corresponding, respectively, to therotational axis of the package and the central axis of the static guideorifice that is perpendicular to the plane of the orifice. TABLE 2 MeanMax. Angle Range Tension Tension Fiber (degree) Tension (g) (grams)Spikes Tack T-127 0 38.4 174.9 56 620 dtex 5 40.8 176.5 85 Lot 9291 11BROKE Merge 1Y331 22 BROKE 45 BROKE T-127 0 16.5 118.4 0 620 dtex 5 17.3119.2 0 Lot 0211 11 17.3 122.4 0 Merge 16398 22 18.8 124.7 0 45 20.4131.8 0 57 25.1 138.0 1 67 29.0 149.0 9 77 30.6 156.9 11 90 35.3 167.914 T-162B 22 32.9 171.8 16 11.368 800 dtex 45 40.8 198.4 53 ″ Lot 020557 44.7 >200 72 ″ Merge 16525 T-162C 22 25.9 159.2 0 7.02 800 dtex 4529.8 176.5 4 ″ Lot 0020 57 31.4 169.4 24 ″ Merge 16600

[0065] Examination of the data in the above table reveals an unexpectedrelationship between threadline tension and the angle between thecenterlines of the package and the static guide. As the angle increasesso does thread line tension, and tension spikes occur more frequently.At sufficiently large angles, thread line breakage can occur. Thesensitivity of thread line tension to the angle traversed by the threadline as it passes through the guide is dependent upon the properties ofthe fiber. The data of Table 2 indicate that fibers characterized byhigher tack exhibit higher sensitivity of thread line tension withrespect to this angle. For some fibers that exhibit an exceptionallyhigh level of tack, the angle above which thread line breakage cannot beavoided is less than about 10°.

EXAMPLE 3

[0066] The series of runs, using the test equipment described previouslyand configured as in Example 2, evaluated the effect of angle onthreadline tension for fibers of different tack levels. The distance, d,between the package and the static guide was maintained constant at 0.65meter. Threadline draft was maintained at 4×by controlling the firstdriven roll and the takeup rolls, respectively, at surface speeds of68.6 and 274.3 meters/min. All other experimental conditions were asdescribed for Example 2. The data are summarized in Table 3. TABLE 3Mean Max. Angle Range Tension Tension Fiber (degree) Tension (g) (grams)Spikes Tack 0 25.1 164.7 2 7.02 T-162C 5 25.1 157.7 0 ″ 800 dtex 11 27.5156.9 0 ″ Merge 16600 22 28.2 160.0 0 ″ Lot 0020 45 36.9 182.8 16 ″ 5742.4 196.1 59 ″ 67 47.8 >200.0 127 ″ 77 BROKE 0 18.0 150.6 0  1.408T-162C 5 15.7 142.8 0 ″ As-spun 11 17.3 143.5 0 ″ 840 den 22 14.9 140.40 ″ Merge 16795 45 14.9 138.8 0 ″ Lot 1019 57 ″ 67 15.7 140.4 0 ″ 7716.5 144.3 0 ″ 90 17.3 145.1 0 ″ 0 29.0 171.8 13 11.368 T-162 B 5 32.2172.6 10 ″ 800 dtex 11 36.1 184.3 42 ″ Merge 16525 22 39.2 >200.0 43 ″Lot 0205 45 52.6 >200.0 126 ″ 57 BROKE ″

[0067] The high tack fibers tested in this series of runs are the sameas two of the fibers tested in Example 2. Comparison of the data forthese same fibers in Tables 2 and 3, shows that thread line tensionincreases with increasing angle, and thread line breakage may occur atexcessively high angles. (In contrast, fibers containing finish can berun at angles of up to and including 900 with no increase in thread linetension, no occurrence of tension spikes and no thread line breaks. WhenLycra®XA® T-162C fiber, 924 dtex den, merge 16795(lot 1019), finish,having a tack of 1.406, was run at angles of 0-90°, there was nothreadline tension increase and no tension spikes.)

[0068] These data demonstrate that limiting the angle the thread linetraverses as it passes through the first static guide providesuninterrupted manufacturing processing even for high tack fiberthreadlines.

EXAMPLE 4

[0069] This series of runs using the test equipment described previouslyand configured as in Example 2, evaluated the effect of the distance, d,between the package and the static guide on threadline tension forfibers of different tack levels. The angle, θ, was maintained constantat 220. The threadline draft was controlled at 4× and the take-up speedat 274.3 meters/m in. TABLE 4 Mean Max. Distance Range Tension TackFiber (meter) Tension (g) (grams) (grams) T-162 C 0.20 56.5 >200 7.02As-spun 0.30 44.7 200.0 ″ 720 den 0.41 32.2 182.0 ″ Merge 16600 0.5132.2 174.9 ″ Lot 0020 0.61 31.4 181.2 ″ 0.71 29.0 173.3 ″ 0.81 29.8178.8 ″ 0.91 32.2 173.3 ″ 1.02 29.0 167.9 ″ T-162 B 0.20 BROKE BROKE11.368 As-spun 0.30 57.3 >200 ″ 720 den 0.41 56.5 >200 ″ Merge 165250.51 55.7 >200 ″ Lot 0205 0.61 56.5 200.0 ″ 0.71 56.5 200.0 ″ 0.81 48.6200.0 ″ 0.91 50.2 200.0 ″ 1.02 52.6 200.0 ″

[0070] The test results for these fibers show the minimum distancebetween the package and the fixed guide below which the threadlinetension and mean range tension increase unacceptably. The value of thisminimum depends upon the tack level of the fiber being tested. Incontrast, there is essentially no effect of package-to-static guidedistance on the lower tack Lycra® spandex. These results reinforce thedifficulty in maintaining smoothly running process conditions with hightack fibers.

[0071] The present invention allows successful control of processesutilizing such fibers.

EXAMPLE 5

[0072] A test of the operation of the unwinder system of this invention,as pictured in FIGS. 2-5, was conducted under commercial productionconditions using fibers that were characterized by different levels oftack. Table 5 summarizes these test results. Data were obtained as inprevious examples, except that each of the tension measurements reportedis the average of a minimum of 4 separate measurements, each measurementconsisting of one tube running for a 10-min period. Similarly, eachnumber of tension spikes, as reported in Table 5, is the average numberof spikes greater than 25 grams above baseline tension in a 10-minperiod. Measurements were made on packages that were nearly full(surface) or nearly empty (core). Core measurements are those with about1.6-cm thickness of yarn remaining on the tube. Of the 5 as-spun fibersrun, 4 ran with no operational problems. One fiber sample, Merge 1Y331,did result in an unacceptable occurrence of tension spikes. That fiberdemonstrated an unusually high level of tack, even for as-spun fiber, asevidenced by the fact that the mean range tension was over 60% higherthan that of the fiber exhibiting the next highest level of tack. TABLE5 Mean Linear Yarn Range Max. Density Location Speed Yarn TensionTension Tension Fiber (dtex) on Tube (ft/min) Draft (grams) (grams)Spikes Merge 16398 620 Surface 274.3 4X 12.3 100.6 0 Merge 16398 620Surface 121.9 4X 12.5 96.1 0 Merge 16398 620 Core 274.3 4X 17.5 110.7 0Merge 16398 620 Core 121.9 4X 16.3 104.1 0 Merge 1Y331 620 Surface 274.34X 28.6 151.4 18

What is claimed is:
 1. An unwinder comprising: a) a frame; b) a fiberpackage holder affixed to said frame; c) a fiber package held on thefiber package holder about a rotational axis such that at least onefiber can unwind from said fiber package in a direction defining anacute angle with the rotational axis of the fiber package; d) a driventake-off roll for unwinding said at least one fiber from the fiberpackage; and e) a first fiber guide for directing said at least onefiber as said at least one fiber is unwound from the fiber package, saidfirst fiber guide defining a fiber guide inlet orifice having a centralaxis and positioned on said frame such that: i. a distance (d) from thefirst fiber guide to a front end of the fiber package facing said firstfiber guide, measured on the line defined by the rotational axis of thefiber package, is equal to: 1) at least about 0.41 meter when said atleast one fiber has tack greater than about 2 grams OETO and less thanabout 7.5 grams OETO; or 2) from about 0.71 meter to about 0.91 meterwhen said at least one fiber has tack greater than about 7.5; and ii. anangle (θ), defined by the intersection of imaginary lines corresponding,respectively, to the rotational axis of the package and the central axisof the fiber guide inlet orifice is equal to: 1) 0° to about 30° whensaid at least one fiber has tack greater than about 2 grams OETO andless than about 7.5 grams OETO; or 2) 0° to about 10° when said at leastone fiber has tack greater than about 7.5 grams OETO.
 2. The unwinder ofclaim 1 further comprising a second fiber guide positioned between saidfiber package and said first fiber guide for directing said at least onefiber as said at least one fiber is unwound from the fiber package. 3.The unwinder of claim 2 further comprising a third fiber guidepositioned between said first fiber guide and said driven take-off roll.4. The unwinder of claim 3 further comprising a fourth fiber guidepositioned between said third fiber guide and said driven take-up roll.5. The unwinder of claim 1 wherein said first fiber guide comprisescomprises a grooved roll.
 6. The unwinder of claim 1 wherein said firstfiber guide comprises a circular guide having a wear-resistant surfacefor contacting the fiber.
 7. The unwinder of claim 6 wherein saidwear-resistant surface is the inner surface of an annulus.
 8. Theunwinder of claim 1 wherein said first fiber guide is a static guide. 9.A method for unwinding fiber from a fiber package comprising the stepsof: a. holding the fiber package about a rotational axis such that atleast one fiber can unwind from the fiber package in a directiondefining an acute angle with the rotational axis of the fiber package;b. unwinding fiber from the fiber package; c. controlling the directionof said at least one fiber by passing said at least one fiber through afirst static fiber guide having an orifice with a central axis that isperpendicular to the plane of the orifice; d. establishing the distance(d) from said first static fiber guide to a front end of said fiberpackage facing said fiber guide, measured on the line defined by therotational axis of the fiber package, such that said distance (d) isequal to: i. at least about 0.41 meter when said at least one fiber hastack of greater than about 2 grams OETO and less than about 7.5 gramsOETO; or ii. from about 0.71 meter to about 0.91 meter when said atleast one fiber has tack greater than about 7.5 grams OETO; and e.setting an angle (θ), defined by the intersection of imaginary linescorresponding, respectively, to the rotational axis of the package andthe central axis of said first fiber guide, such that said angle (θ) isequal to: i. 0° to about 300 when said at least one fiber has tackgreater than about 2 grams OETO and less than about 7.5 grams OETO; orii. 0° to about 100 when said at least one fiber has tack greater thanabout 7.5 grams OETO.
 10. The method of claim 9 further comprisingproviding a second fiber guide positioned between said fiber package andsaid first static fiber guide for directing said at least one fiber assaid at least one fiber is unwound from the fiber package.